1. Field of the Invention
The present invention relates to surface acoustic wave filters, surface acoustic wave filter devices, and duplexers. The present invention particularly relates to surface acoustic wave filters that include a plurality of longitudinally coupled resonant filters, as well as to surface acoustic wave filter devices and duplexers that include such surface acoustic wave filters.
2. Description of the Related Art
A conventional surface acoustic wave filter is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2006-186433, which discloses a configuration in which a plurality of longitudinally coupled-type surface acoustic wave filters are disposed along a propagation direction of surface acoustic waves and electrically connected in parallel, and reflectors are shared between mutually adjacent longitudinally coupled-type surface acoustic wave filters. Japanese Unexamined Patent Application Publication No. 2006-186433 further discloses that when the number of electrode fingers in reflectors that are not shared is taken as N, it is desirable for the number of shared reflectors to be no less than 2 and less than 2N.